The proposed research involves fluorescence studies of drug-DNA adducts and proteins. The complicated emissions from these systems will be resolved by global analysis of time-resolved fluorescence decay data obtained under different experimental conditions. The interaction of pyrrolo(1,4)- bensodiazepine antitumor antibiotics with DNA will be characterized using spectroscopic and hydrodynamic techniques. The effects of DNA sequence and conformation on the covalent drug-DNA interaction will be investigated in fluorescence and CD experiments with synthetic and natural DNAs. The effects of drug binding on DNA solution conformation will be determined by static and dynamic light scattering. These antibiotics provide a new fluorescent probe for rapid internal motions in the DNA double helix. DNA dynamics will be studied by fluorescence depolarization measurements in the time as well as frequency domains. The emission anisostropy data for covalent drug-DNA adducts will be analyzed according to the predicted nonexponential decay law. The effects on the dynamics of factors influencing DNA structure will be examined. Two enzymes involved in nucleic acid metabolism will be investigated by steady-state and time-resolved fluorescence measurements. The interactions of terminal transferase with monomer and polymer substrates and of adenosine deaminase with ground-state and transition-state inhibitors will be characterized. The effects of ligand binding on protein conformation nand dynamics will be determined. The above research is aimed at elucidation of the role of DNA flexibility in biological function. It also offers insight into the mechanism of action of antitumor antibiotics and of enzymes important in human leukemia.